1. Technical Field
The present invention relates to image processing, and in particular, it relates to methods for AWB (Automatic White Balance) compensation and apparatuses using the same.
2. Description of the Related Art
HDR (High Dynamic Range) images can show a greater range of luminance levels captured in real-world scenes, from direct sunlight to a faint nebula. It is often achieved by capturing and then combining different exposures of the same subject matter. Non-HDR cameras take photographs with a limited exposure range, resulting in the loss of detail in saturate or dark areas. HDRM (High Dynamic Range Merging) compensates for this loss of detail by capturing multiple photographs at different exposure levels and combining them to produce a photograph representative of a broader tonal range. LDR (Low Dynamic Range) images each may contain parts with different color temperatures and it will produce a color-biased HDR image if fusing the LDR images directly. AWB (Automatic White Balance) adjusts gains of color channels to correct the color bias resulting from differences in the ambient illumination conditions, thereby enabling an image to be obtained to reflect realistic colors. Conventionally, a unified AWB is applied to the overall image frame. However, an image frame usually contain parts with different color temperatures, thus a unified AWB applying to parts with different color temperatures cannot compensate the color bias to appear neutral in the reproduction. Thus, methods for AWB compensation and apparatuses using the same are introduced to improve the AWB accuracy of the generated HDR image.